Grenade fuze



July 11, 1961 H. R. KOLLMEYER 2,991,717A

GRENADE FUZE Filed Dec. 1. 1954 2 sheets-sheet 1 :Fg -1- Y gli- INVENTOR.

Herman R. Kollmeyer July 11, 1961 H. R. KOLLMEYER GRENADE FUZE Filed D'eC.

2 Sheets-Sheet 2 INVENTORS ZO-o [8 Y Herman R. Kollmeyer .HTTURNE Y5.

Unite d The invention described herein may be manufactured by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to grenades and more particularly to grenade fuzes.

Grenade fuzes used previously were purely of the time variety. 'Ihat type of fuze has the disadvantage that it sometimes gives the enemy the time and opportunity to return the grenade before it functions.

One object of the present invention is a grenade fuze which functions on impact or at the expiration of a predetermined period whichever is later.

Another object of the invention is a fuze which remembers an impact occurring prior to the expiration of the predetermined period and functions 'the grenade at the expiration of that period.

Another object of the invention is a fuze which functions the grenade upon impact should impact occur subsequent to the expiration of the predetermined period.

Another object of the invention -is to provide the fuze with a safe arming period means.

Another object of the invention is a fuze which provides complete handling safety.

Another object of the invention is a fuze which is economical to mass production.

Another object of the invention is a fuze which is highly reliable.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from the following description and drawings in which:

FIGURE 1 is a schematic View illustrating a fuze construction in accordance with the invention as applied to a hand grenade.

FIGURE 2 is an enlarged perspective view, partly in section, of the fuze provided with the memory feature.

FIGURE 3 is a cross sectional view of the invention taken on line 3 3 of FIG, 2.

States Patent C) FIGURE 4 is a cross sectional view of the invention l taken on l-ine 4 4 of FIG. 2.

FIGURE 5 is a cross sectional view of the invention taken on line 5 5 of FIG. 2.

FIGURE 6 is a cross sectional view of the invention taken on line 6 6 of FIG. 2.

FIGURE 7 is an enlarged perspective view, partly in section, of a modied form of the invention shown in FIG. 2 wherein the memory feature is eliminated,

FIGURES 8 and 9 are detailed views of the detonator rotor arming means in the unarmed and the armed positions, respectively.

FIGURE 10 is a cross sectional view of the detonator rOtor arming means taken on line 10 1(i of FIG. 8.

The fuze shown -in FIG. 1 and indicated generally by numeral 11 has a memory feature which enables the fuze to remember an impact occurring subsequent to the expiration of the safe arming period, approximately 3%; second, but prior to the expiration of a predetermined delay period, approximately 2 seconds in the present embodiment of the invention. The fuze causes the grenade 14 to function at the end of that 2 second period provided a grenade impact has occurred `subsequent to the expiration of the safe arming period. After 2 seconds the fuze functions upon grenade impact.

Fuze 11 is positioned between the two sections 12 and 21,991,717 Patented July l1, 1961 13 of grenade 14, FIG. l, and within cavity 15 provided partly in each section. The fuze comprises body 16, FIGS. 1 and 2, having a detonator rotor 17 rotatably mounted therein by means of shaft 18, FIG. l0, extending through a pair of apertures 19a and 20a provided in iianges 19 and 20, respectively, of said rotor, the shaft being journaled within the base portion 21 of body 16. Explosive detonator 17a -is housed Within cavity 17b of detonator rotor 17.

Support plate 22, FIG. 2, rests upon shoulder 23 provided in body 16, internal ring gear 24 resting upon said plate. Gear 24 rotates relative to plate 22. Internal ring gear 24 supports thereupon main drive spring housing 25. Contained within the housing is main drive Spring 26, the enlarged outer end 27 of which engages slot 28 in housing 25, the other end of the spring being affixed to striker tube 29 so that the housing will rotate when the spring is wound or unwound. A conventional clutch arrangement, not shown, engages internal ring gear 24 and housing 25 in such a manner that the gear will turn with the housing when the spring unwinds but will not turn with the housing when the spring is wound. That arrangement has the purpose of allowing the spring to be wound free of restraint by those mechanisms, to be described hereinafter, which are driven by the internal ring gear. The speed of rotation of the ring gear is regulated by escapement means 30, FIG. 5, comprising a star wheel 31 and double pallets 32 and 33. Pinion 34, engaged `with internal ring gear 24, and star wheel 31, are mounted upon and turn with shaft 45 which is journaled within base portion 21. As best seen in FIGS. 8, 9 and 10, internal ring gear 24 drives pinion 37, said pinion being affixed to and adapted to turn with shaft 18. Shaft 18 is provided with threaded portion 318 upon which square nut 39 is adapted to ride in slidable relationship to detonator rotor 17. Square nut 39 is disposed between fiat surface 40 of rotor 17 and iiat surface 41 of block 42 when the fuze is in the unarmed condition. The nut must move forward so as to clear the top at surface 43 of block 42 before rotor 17 can move into the armed position,

Forming an integral part of and depending from main drive spring housing 25 is trigger tube 44, FIG. 2, the said tube being adapted to turn with spring housing 25. Plunger 45 is concentric with and axially slidable within trigger tube 44, the plunger adapted to turn with said tube by means of a linkage comprising pin 46 aixed to said plunger and elongated slot 47 formed in trigger tube 4 4, the said pin adapted to move forward and rearward within `said slot.

Striker tube 29, concentric with plunger 45, is positioned within said plunger, the plunger adapted to turn and to slide relative to said striker tube, the striker tube being aiiixed to support plate 22. Striker 48, having stabber 48a axed thereto, is slidably positioned within striker tube 29. Helical spring 36, concentric with striker 48, urges the suiker rearwardly and urges plunger 45 forwardly, the striker being normally maintained in the forward portion of the striker tube by means of trigger pin 49, having beveled head 49a, which engages both the annular groove 50y provided in the striker and aperture 51 provided in the striker tube. Groove 50 has beveled edge 50a which cooperates with pin 49 in a manner described hereinafter,

Plunger 45 is provided with a circumferential `groove 52 encompassing somewhat less than 360 degrees of the inner surface of the plunger, the groove terminating in aperture 53.

Pin 54, aixed to striker tube 29, is adapted to engage slot 55 provided in plunger 45 for the purpose of preventing the plunger and the trigger tube from turning relative to the striker tube and to prevent the fuze from prematurely arming when the plunger is in the depressed position compressing helical spring 36.

Plunger 45 is normally maintained in the unarmed depressed position, slot 55 engaging pin 54, when the two sections 12 and 13 of the grenade 14 are abutting. When the safety pin, not shown, is extracted from the grenade, and the grenade is thrown or projected, the two sections of the grenade separate by means of helical spring 36 urging plunger 45 forwardly, the said plunger acting against section 12 and base 21 acting against section 13. When the plunger assumes its extended position, pin 54 and slot 55 disengaging from one another, main drive spring 26 causes the movement of main drive spring housing 25, internal ring gear 24, trigger tube 44 and plunger 45, these members being linked together. The speed of the several members is regulated by the star wheel and double pallets escapement 30.

Pinion 37 is driven by internal ring gear 24, shaft 18 turning with said pinion, causing square nut 39 to ride forward upon threaded portion 38 of shaft 18 as the shaft rotates. The nut is prevented from turning with the shaft inasmuch as the nut is disposed between flat surface 40 of detonator rotor 17 and flat surface 41 of block 42. When the nut has moved into engagement with ange 19, it having cleared the top surface 43 of block 42, the nut locks against ange 19' whereupon the nut and detonator rotor 17 move together to the armed position bringing detonator 17a into alignment with stabber 48a.

As main drive spring housing 25 rotates, trigger tube 44, depending therefrom, rotates also, and the trigger tube, being linked to plunger 45 causes that member to turn. After plunger 45 has rotated for a period of approximately second, groove 52 moves into alignment with trigger pin 49. An impact of the grenade with an object will cause plunger 45 to be depressed. If that impact occurs subsequent to the expiration of the 3A second period the trigger pin 49 is in a position to move into groove 52 locking plunger 45 in the depressed position. The action by which trigger pin 49 is caused to enter groove 52 is as follows: when plunger 45 moves rearwardly, helical spring 36 is compressed, whereupon the spring urges striker 4S rearwardly. Beveled edge 50a of groove 50 in striker 48 acts against the beveled head 49a of pin 49 urging said pin in an outwardly direction, the pin moving into groove 52.

Plunger 45 continues to rotate relative to striker tube 29 and trigger pin 49 until the pin and aperture 53 make contact at the expiration of the ysaid Z-second period, whereupon the pin moves into said aperture releasing striker 48 to be driven rearward by helical spring 36. At the end of its -rearward travel stabber 48a engages, penetrates, and functions detonator 17a, said detonator, in turn, functioning the booster charge, not shown, aperture 21a providing the ignition path. The booster, in turn, sets off the high explosive filler, not shown, of the grenade 14.

Should the grenade impact with an object subsequent to the expiration of the 2-second period, aperture 53 having rotated into alignment with trigger pin 49, and upon plunger 45 being depressed, trigger pin 49 will move through groove 52 into aperture 53, whereupon striker 48 is released causing stabber 48a to be driven rearwardly as before by helical spring 36 to yfunction `detonator 17a.

An impact of the grenade with an object occurring prior to the expiration of the 3A second safe arming period will not result in plunger 45 being locked in the depressed position by trigger pin 49 inasmuch as, prior to the end of that period, groove 52 and' trigger pin 49 are not in alignment. That is a safety feature whereby a grenade, which is dropped to the groundby a soldier who is shot prior to throwing the grenade but subsequent to the extraction of the safety pin, is not functioned by the fuze to the detriment of `friendly troops. It has been calculated that a period of less than second is required for a grenade to travel fromA the hand of an average size man to the ground after being dropped.

Detonator rotor 17 is adapated to move into the armed position aligning detonator 17a and stabber 48a just prior to the expiration of the 2-second period so that a premature release of striker 48 prior to the expiration of that 2- second period will not result in an unwanted fuze function.

FIG. 7 shows `a modification of the invention wherein the memory feature is eliminated. The detonator rotor 17 containing explosive detonator 17a is mounted upon base 21 of fuze 11a. The escapement 30a shown in FIG. 7 has a star wheel 31 and a single pallet 32a. Only one pallet is needed in the modified version to facilitate the more rapid movement of detonator rotor 17 into the armed position. Internal ring gear 24 is slidably positioned upon support plate 22, the support plate resting upon shoulder 23 of the body 16a. Pinion 37 is driven by internal ring gear 24, the said gear being driven by main drive spring 26 through main drive spring housing 25. Plunger tube 29a is supported at the Vtwo ends thereof by support plate 22 and cover plate 56 respectively. Plunger 45a, concentric with plunger tube 29a and slidable therein is biased forwardly lby helical spring 36a which acts against shoulder 57 of plunger tube 29a and against the closed end 58 of plunger 45a. Plunger 45a has stabber 59 affixed to closed end 58, the point 60 of said stabber being directed rearwardly. Leaf spring 61 affixed to support plate 22, as indicated at 62, extends inwardly, the free end 63 thereof being in alignment With shoulder 64 of -stabber 59.

As in the case of the memory version fuze, the moditied fuze 11a is positioned between two sections of a split grenade in the same manner as shown in FIG. l, the fuze well of the grenade being somewhat more shallow than the fuze well 15 of the grenade containing the memory version fuze.

Normally the two sections of the grenade are abutting, the grenade being held in that position by a safety pin, not shown. The grenade, when in the normal position, serves to maintain plunger 45a in the depressed position compressing helical spring 36a. With detonator rotor 17 in the unarmed position, the detonator 17a being out of alignment with stabber 59, and plunger 45a depressed, shoulder 64 of the stabber acts against the free end 63 of leaf spring `61 bending the spring rearwardly so that the spring engages the teeth of star wheel 31 to lock the wheel in a stationary position. Drive spring housing 25, internal ring gear 24, and pinion 34, linked to the star wheel, are restrained in the unarmed position thereby.

When lthe grenade is thrown or launched, the grenade safety pin, not shown, having been extracted, helical spring 36a forces plunger 45a into the extended position separating the two sections of the grenade and removing the engagement of stabber 59 with leaf spring 61. The spring then assumes its unflexed position out of engagement with the teeth of star wheel 31 permitting main drive spring 26 to drive main drive spring housing 25 and internal ring gear 24. The speed of rotation of the ring gear is regulated by the star wheel and pallet escapement 30a through pinion 34.

As internal ring gear 24 turns, pinion 37, engaged with the gear, turns also causing shaft 18 to turn and square nut 39 to ride forward upon threaded portion 38 of shaft 18 and between the flat surface 40 of detonator rotor 17 and the flat surface 41 of block 42, FIGS. 8, 9 and l0. Square nut 39 moves to a position engaging flange 19 of detonator rotor 17, the said nut having cleared the top surface 43 of block 42, and locks against the flange whereupon the nut turns carrying detonator rotor 17 into the armed position aligning detonator 17a with stabber 59. In this embodiment of the invention the period elapsing between grenade launching and the movement of detonator 17a into alignment with stabber 59 is approximately second.

If the grenade, thrown in a normal manner, impacts with an object before the expiration of the 3A second period, the fuze does not function inasmuch as the detonator and the stabber are not in alignment. An impact occurring subsequent to the expiration of the 3A second period results in the striker being driven rearwardly against the urging of helical spring 36a so that the point 60 thereof engages and penetrates detonator 17a causing the ignition of the booster charge, not shown, and the high explosive filler of the grenade, not shown, in the same manner that the detonator in the memory version fuze functions the booster and the high explosive filler of its grenade.

It will be apparent that the embodiments shown are only exemplary and that various modifications can be made in construction and arrangement within the scope of the invention as defined in the appended claims.

I claim:

1. In a split grenade having a cavity provided in the two sections thereof, a grenade fuze positioned within said cavity, the fuze comprising a body, a detonator rotor rotatably mounted within said body and having an explosive detonator housed therein, a plunger tube affixed to said body and having a plunger slidably positioned therein, a stabber affixed to said plunger, the point thereof directed rearwardly, means for biasing said plunger forwardly within said plunger tube, means for normally maintaining said rotor in the unarmed position with the detonator out of alignment with the stabber, means for moving the rotor into the armed position aligning the detonator with the stabber, said alignment occurring at the expiration of the safe arming period, and means for regulating the detonator rotor arming means, the fuze adapted to function upon grenade impact when the two sections of the grenade move into abutting positions causing the plunger to be driven rearwardly, the stabber point engaging and activating the detonator thereby, the means for maintaining the fuze normally unarmed comprises a leaf spring, one end of said spring being anchored within the fuze body, the free end being in alignment with the rearward shoulder of the stabber, and a starwheel associated with the detonator arming means in such a manner that binding the starwheel will prevent the rotor from turning, the stabber adapted to act against the free end of the spring to move the spring into engagement with the starwheel teeth when the plunger is in the depressed position, that engagement serving to maintain the starwheel stationary and prevent the detonator rotor from moving into the armed position.

2. In a split grenade having a cavity provided in the two sections thereof, a grenade fuze positioned within said cavity, the fuze comprising a body, a detonator rotor rotatably mounted within said body and having an explosive detonator housed therein, a plunger tube affixed to said body and having a plunger slidably positioned therein, a stabber affixed to said plunger, the point thereof directed rearwardly, means for biasing said plunger forwardly within said plunger tube, means for normally maintaining said rotor in the unarmed position with the detonator out of alignment with the stabber, means for moving the rotor into the armed position aligning the detonator with the stabber, said alignment occurring at the expiration of the safe arming period, and means for regulating the detonator rotor arming means, the fuze adapted to function upon grenade impact when the two sections of the grenade move into abutting positions causing the plunger to be driven rearwardly, the stabber point engaging and activating the detonator thereby, the detonator rotor arming means comprises a rotor provided with one at surface, a block affixed to the fuze body and having a at surface in parallel spaced relationship with the flat surface of the unarmed rotor, a threaded shaft journaled within the fuze body upon which the rotor is adapted to turn, a square nut positioned upon the threaded shaft in slidable relationship with the two flat surfaces, the nut adapted to move forward upon the shaft as the shaft turns, a pinion aiiixed to the forward end of the shaft, a ring gear slidably supported within the fuze body and engaged with the pinion, and a spring and spring housing assembly releasably engaging the gear, the assembly adapted to drive the gear whereupon the pinion is caused to turn, the shaft turning therewith, and `the nut riding forward upon the shaft and engaging the rotor at the end of its travel, the nut having cleared the top of the block, whereupon the nut, shaft, and rotor turn together, the rotor moving into the armed position aligning the explosive detonator and the stabber.

3. In a split grenade having a cavity provided in the two sections thereof, a grenade fuze positioned within said cavity, the fuze comprising a body and a detonator rotor rotatably mounted within said bod-y, the detonator rotor having an explosive detonator housed therein, means for releasably maintaining the rotor in the unarmed position oset from the longitudinal axis of the fuze, means for moving the rotor into the armed position at the expiration of a predetermined delay period, a iirst tube rotatably secured to the fuze body, means adapted to rotate said first tube, a plunger concentric with and axially slidable within said first tube but adapted to turn with the first tube by a linkage comprising a pin and slot arrangement, said plunger being provided with a circumferential groove encompassing somewhat less than 360 degrees of the inner surface thereof, said groove terminating in an aperture in the wall of the plunger, a second tube positioned within and concentric with said plunger and affixed to the fuze body, a striker slidably positioned within said second tube and having a stabber affixed thereto, the point of which stabber is directed rearwardly, said striker being biased rearwardly, a trigger pin engaging the plunger groove and the striker groove to normally maintain the striker within the forward portion to the second tube, and means adapted to regulate the speed of rotation of the first tube and plunger and the detonator rotor arming means, the rotor, upon grenade launching and at the expiration of the predetermined delay period, adapted to move into the armed position aligning the explosive detonator and the stabber, the first tube and plunger adapted to rotate through a predetermined angle so that on grenade impact, when the plunger is driven rearwardly, the plunger will be locked in the depressed position by the trigger pin entering the groove, the pin thereafter moving into the aperture to release the striker when the pin and aperture come into alignment at the expiration of the predetermined delay period, the striker, upon being released, adapted to move rapidly rearwardly to engage and function the explosive detonator.

4. In a split grenade fuze, a detonator rotor arming means comprising a rotor provided with one flat surface, a block aixed to the fuze body and having one liat surface in parallel spaced relationship with the flat surface of the unarmed rotor, a threaded shaft journaled within the fuze body upon which the rotor is adapted to turn, a square nut positioned upon the shaft in slidable relationship with said flat surfaces, the nut adapted to move forward upon the shaft as the shaft turns, a pinion affixed to the forward end of the shaft, a ring gear slidably supported within the fuze body and engaged with the pinion, and a spring and spring housing assembly engaging the gear, the assembly adapted to drive the gear whereupon the pinion is caused to turn, the shaft turning therewith, and the nut riding forward upon the shaft and engaging the rotor at the end of its travel, the nut having cleared the top of the block, whereupon the nut, shaft, and rotor turn together, the rotor moving into the armed position aligning the explosive detonator and the stabber.

References Cited in the file of this patent UNITED STATES PATENTS 1,665,666 Junghans Apr, l0, 1928 2,718,850 Kuhn Sept. 27, 1955 FOREIGN PATENTS 110,915 Great Britain Nov. 6, 1917 

